Distributed maximum power point tracking system, structure and process

ABSTRACT

Distributed maximum power point tracking systems, structures, and processes are provided for power generation structures, such as for but not limited to a solar panel arrays. In an exemplary solar panel string structure, distributed maximum power point tracking (DMPPT) modules are provided, such as integrated into or retrofitted for each solar panel. The DMPPT modules provide panel level control for startup, operation, monitoring, and shutdown, and further provide flexible design and operation for strings of multiple panels. The strings are typically linked in parallel to a combiner box, and then toward and enhanced inverter module, which is typically connected to a power grid. Enhanced inverters are controllable either locally or remotely, wherein system status is readily determined, and operation of one or more sections of the system are readily controlled. The system provides increased operation time, and increased power production and efficiency, over a wide range of operating conditions.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.13/250,887, entitled Distributed Maximum Power Point Tracking System,Structure and Process, filed 30 Sep. 2011, which is a Continuation ofU.S. application Ser. No. 12/842,864, entitled Distributed Maximum PowerPoint Tracking System, Structure and Process, filed 23 Jul. 2010, whichwas issued as U.S. Pat. No. 8,035,249 on 11 Oct. 2011, which is aContinuation of U.S. application Ser. No. 12/056,235, entitledDistributed Maximum Power Point Tracking System, Structure and Process,filed 26 Mar. 2008, issued as U.S. Pat. No. 7,772,716 on 10 Aug. 2010,which claims priority to U.S. Provisional Application No. 60/908,361,entitled Distributed Multiple Power Point Tracking, filed 27 Mar. 2007,which are each incorporated herein in their entirety by this referencethereto.

This application is also related to PCT Application No. PCT/US08/58473,Distributed Maximum Power Point Tracking System, Structure and Process,filed 27 Mar. 2008, which claims priority to U.S. application Ser. No.12/056,235, entitled Distributed Maximum Power Point Tracking System,Structure and Process, filed 26 Mar. 2008, issued as U.S. Pat. No.7,772,716 on 10 Aug. 2010, which claims priority to U.S. ProvisionalApplication No. 60/908,361, entitled Distributed Multiple Power PointTracking, filed 27 Mar. 2007.

This application is also related to PCT Application No. PCT/US10/45352,filed 12 Aug. 2010, entitled Enhanced Solar Panels, Liquid DeliverySystems and Associated Processes for Solar Energy Systems, which is aContinuation in Part of U.S. application Ser. No. 12/842,864, entitledDistributed Maximum Power Point Tracking System, Structure and Process,filed 23 Jul. 2010, which is a Continuation of U.S. application Ser. No.12/056,235, entitled Distributed Maximum Power Point Tracking System,Structure and Process, filed 26 Mar. 2008, issued as U.S. Pat. No.7,772,716 on 10 Aug. 2010, which claims priority to U.S. ProvisionalApplication No. 60/908,361, entitled Distributed Multiple Power PointTracking, filed 27 Mar. 2007.

PCT Application No. PCT/US10/45352, filed 12 Aug. 2010, entitledEnhanced Solar Panels, Liquid Delivery Systems and Associated Processesfor Solar Energy Systems, also claims priority to U.S. ProvisionalApplication No. 61/234,181, entitled Distributed Maximum Power PointTracking System Structure, and Process with Enhanced Solar PanelCoating, Cleaning and Cooling, filed 14 Aug. 2009.

The Applicants hereby rescind any disclaimer of claim scope in theparent application(s) or the prosecution history thereof and advises theUSPTO that the claims in this application may be broader than any claimin the parent application(s).

FIELD OF THE INVENTION

The present invention relates generally to the field of power invertersystems. More particularly, the present invention relates to distributedpower system structures, operation and control, and enhanced invertersystems, structures, and processes.

BACKGROUND OF THE INVENTION

Solar power is a clean renewable energy resource, and is becomingincreasingly important for the future of this planet. Energy from theSun is converted to electrical energy via the photoelectric effect usingmany photovoltaic cells in a photovoltaic (PV) panel. Power from a PVpanel is direct current (DC), while modern utility grids requirealternating current (AC) power. The DC power from the PV panel must beconverted to AC power, of a suitable quality, and injected into thegrid. A solar inverter accomplishes this task.

It would be advantageous to provide a structure, system and process toimprove the efficiency of power inverters, such as for a solar panelsystem. Such a development would provide a significant technicaladvance.

To maximize the amount of power harvested, most solar inverters performa maximum power point tracking (MPPT) algorithm. These algorithms treatan entire array of PV panels as a single entity, averaging all of the PVpanels together, with a preference towards the weakest link.

It would therefore also be advantageous to provide a structure, systemand process, to maximize efficiency and harvest capabilities of anysolar PV system, to capitalize on profit and maximum return for theowner of the system.

Three specific examples of DC energy sources that currently have a rolein distributed generation and sustainable energy systems arephotovoltaic (PV) panels, fuel cell stacks, and batteries of variouschemistries. These DC energy sources are all series and parallelconnections of basic “cells”. These cells all operate at a low DCvoltage, ranging from less than a volt (for a PV cell) to three or fourvolts (for a Li-Ion cell). These low voltages do not interface well toexisting higher power systems, so the cells are series connected, tocreate modules with higher terminal voltages. Paralleled modules thensupply increased power levels to an inverter, for conversion to ACpower.

These long strings of cells bring with them many complications. Whilethe current exemplary discussion is focused on PV Panels, other powersystems and devices are often similarly implemented for other sources ofDC power.

A problem occurs when even a single cell in a PV array is shaded orobscured. The photocurrent generated in a shaded cell may drop to around23.2% of the other cells. The shaded cell is reverse biased by theremaining cells in the string, while current continues to flow throughthe shaded cell, causing large localized power dissipation. This poweris converted to heat, which in turn lowers the panel's output powercapability. Bypass diodes, generally placed in parallel around each 24cells (which may vary between manufacturers), limit the reverse biasvoltage and hence the power dissipation in the shaded cell, to thatgenerated by the surrounding half panel. However, all the power fromthat sub-string is lost, while current flows in the bypass diode. Aswell, the bypass diode wastes power from the entire string current,which flows through the panel. The output voltage of the entire stringis also negatively affected, causing an even larger imbalance in thesystem.

Conventional module MPP currents may become unbalanced for otherreasons. PV panels in a string are never identical. Because each PVpanel in a series string is constrained to conduct the same current asthe other PV panels in the string, the least efficient module sets themaximum string current, thereby reducing the overall efficiency of thearray to the efficiency of this PV panel. For similar reasons, PV panelsin a string are conventionally required to be mounted in the sameorientation, and to be of identical size. This is not always possible ordesirable, such as for aesthetic or other architectural reasons.

In standard solar array wiring, several series strings of solar panelsare wired in parallel to each other to increase power. If there is animbalance between these paralleled strings, current flows from thehigher potential strings to the lower potential strings, instead offlowing to the inverter. Just as it is important to match the cellswithin a panel, it is also necessary to match the panels in a string,and then to match the strings, for maximum harvest from the solar array.If small fluctuations in environmental conditions occur, it can have alarge impact on the system as a whole.

Solar inverters also “average” the entire array when they perform aconventional MPPT function. However, it is not a true average, sincethere is a preference that leans towards the weakest link in the system.This means that, even though some panels may be capable of supplying 100percent of their rated power, the system will only harvest a fraction ofthat power, due to the averaging effect of the algorithm, and thecurrent following through the weaker string, panel, and/or cells.

It would therefore be advantageous to provide a means for applying analgorithm that maximizes the harvest of power from a string, panel,and/or cells. Such an improvement would provide a significant advance tothe efficiency and cost effectiveness of power cells structures,processes, and systems.

SUMMARY OF THE INVENTION

Distributed maximum power point tracking systems, structures, andprocesses are provided for power generation structures, such as for butnot limited to a solar panel arrays. In an exemplary solar panel stringstructure, distributed maximum power point tracking (DMPPT) modules areprovided, such as integrated into or retrofitted for each solar panel.The DMPPT modules provide panel level control for startup, operation,monitoring, and shutdown, and further provide flexible design andoperation for strings of multiple panels. The strings are typicallylinked in parallel to a combiner box, and then toward an enhancedinverter module, which is typically connected to a power grid. Enhancedinverters are controllable either locally or remotely, wherein systemstatus is readily determined, and operation of one or more sections ofthe system are readily controlled. The system provides increasedoperation time, and increased power production and efficiency, over awide range of operating conditions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of an exemplary enhanced power modulecomprising a plurality of power cells connected to a distributed maximumpower point tracking module;

FIG. 2 is a schematic view of an exemplary enhanced solar panelcomprising a plurality of solar cells and a distributed maximum powerpoint tracking module;

FIG. 3 is a schematic view of an exemplary photovoltaic solar cellhaving DC output power connections to a DMPPT module;

FIG. 4 is a schematic view of an exemplary solar array comprising aplurality of enhanced solar panels;

FIG. 5 is a schematic block diagram of an exemplary solar panel systemhaving a plurality of strings of enhanced solar panels routed through acombiner box and controlled through a modular power module housinghaving one or more enhanced inverter modules;

FIG. 6 is a schematic block diagram of an alternate exemplary solarpanel system having a plurality of strings of enhanced solar panelshaving string-level combiner modules and routed through a combiner boxand controlled through a modular power module housing having one or moreenhanced inverter modules;

FIG. 7 is a block diagram of an exemplary distributed MPPT circuit;

FIG. 8 is a first graph showing exemplary current-voltage (IV) curves ofphotovoltaic solar panels over a range of temperatures;

FIG. 9 is a second graph showing exemplary current-voltage (IV) curvesof photovoltaic solar panels over a range of temperatures;

FIG. 10 is time chart of voltage output for an enhanced power modulehaving DMPPT module;

FIG. 11 is a flowchart of an exemplary operation of an enhanced powermodule having a DMPPT module;

FIG. 12 is a schematic view of an exemplary solar array comprising aplurality of solar panels, wherein a portion of the panels in one ormore strings further comprise DMPPT modules;

FIG. 13 shows the relative proportion and size of an exemplary solararray having a capacity of approximately 170 W, comprising a pluralityof enhanced solar panels, wherein a portion of the panels in one or morestrings further comprise DMPPT modules;

FIG. 14 is a block diagram of a modular power module housing having oneor more enhanced inverter modules, a central interface, and connectableto one or more local or remote monitoring or control devices;

FIG. 15 is a block diagram of a modular power module housing having twosub-modules installed;

FIG. 16 is a block diagram of a modular power module housing havingthree sub-modules installed;

FIG. 17 is a block diagram of a modular power module housing having afour sub-module installed;

FIG. 18 is a simplified schematic circuit diagram of an exemplary powersection for an enhanced inverter module;

FIG. 19 shows resultant output power signal properties for activeelimination of harmonics by inverter signal modification usingsine-weighted pulses;

FIG. 20 is a schematic circuit diagram of an exemplary self-powersection of a DMPPT module;

FIG. 21 is a schematic circuit diagram of an exemplary boost circuit fora DMPPT module;

FIG. 22 is a schematic circuit diagram of an exemplary current sensorfor a DMPPT module;

FIG. 23 is a schematic circuit diagram of an exemplary voltage sensorfor a DMPPT module;

FIG. 24 is a schematic circuit diagram of an exemplary output safetyswitch for a DMPPT module;

FIG. 25 is a schematic circuit diagram of an exemplary crowbar circuitfor a DMPPT module;

FIG. 26 is a schematic block diagram showing microprocessor-basedenhancement of an inverter, such as to eliminate one or more levels ofharmonics;

FIG. 27 is flowchart of exemplary operation of an enhanced inverter;

FIG. 28 is an exemplary user interface for monitoring and/or control ofan enhanced power harvesting system comprising power modules havingDMPPT modules; and

FIG. 29 shows an enhanced power harvesting system located on the Earth,wherein one or more panels within a string have different angles and/ororientations.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 is a schematic view of an exemplary enhanced power module 10comprising a plurality of power cells 12, e.g. 12 a-12 n, such as butnot limited to photovoltaic solar cells, fuel cells, and battery cells,connected 16,17 to a distributed maximum power point tracking (DMPPT)module 18. FIG. 2 is a schematic view of an exemplary enhanced powerstructure 10, e.g. an enhanced solar panel 10, comprising a plurality ofsolar cells 12 and a distributed maximum power point tracking module 18.FIG. 3 is a schematic view 30 of an exemplary photovoltaic solar cellhaving DC output power connections 17 to a DMPPT module 18. FIG. 4 is aschematic view of an exemplary solar array 34 comprising a plurality ofenhanced solar panels 10, e.g. 10 a-10 k, arranged in a plurality ofstrings 36, e.g. 36 a-36 n.

The exemplary DMPPT module 18 seen in FIG. 1 has DC inputs 17, and a DCoutput 21, such as comprising a positive lead 19 a and a negative lead19 b, The exemplary DMPPT module 18 also comprises a communicationsinterface 20, and means for connection to a temperature sensor 24, suchas responsive to a local panel temperature 23.

DMPPT modules 18, such as seen in FIG. 1, are preferably locally poweredfrom the solar panel 10 that they are attached to, wherein each DMPPTmodule 18 draws its operating power from it's respective panel 10 thatit is connected to, such as to reduce wiring and to improve efficiency.

DMPPT modules 18 are currently implemented for both new panels 10, i.e.at the point of manufacture, and for existing systems, wherein the DMPPTmodules 18 may be retrofitted to existing panels 10. As also seen inFIG. 1, the external DC connection 21, comprising leads 19 a,19 b, issimilar to the input DC connection 17, such as provided by an existingconventional panel. Therefore, wiring for the DMPPT modules is similarto conventional solar panels, which minimizes the learning curve forinstallation personnel.

The communications link 22 shown in FIG. 1 may be a wired connection ora wireless connection, such as to provide flexibility in design andinstallation. For example, the DMPPT module 18 can communicate via awireless network, or through a wired connection, e.g. single twistedpair standard RS485 cable.

Some embodiments of either the wired or wireless style DMPPT modulesfeature a self-discovery function, such that when a new DMPPT module 18is added to a system 40 (FIGS. 5, 6, 14), the system server 153 (FIG.14) discovers the new module 18 over the communications link 22, andadds the new module 18 and associated panel 10 to the system 40.

As well, some embodiments of wireless style DMPPT modules 18 feature aself-healing function, wherein a DMPPT module 18 having a wirelesscommunication link 22 also has the ability to bypass non-functioningdevices or branches.

For example, if a DMPPT Module 18 is broken or removed, such as by athief, in a wireless system 40, everything continues to function. Thesystem 40 sees the “broken” device 18, and continues normalcommunications with the other DMPPT modules 18. This ensures continuouscommunications with the other active DMPPT modules 18 in the system 40.In a wired system, this may typically cause the loss of communicationswith several modules 18, as the communications line 22 could be damaged,broken, or cut. In addition to the DMPPT modules 18 and inverters 54,other devices may preferably be connected to the wireless network 22. Ifsomething should happen to one of these, it will not affect the system40 as a whole. Therefore, some system embodiments 40 comprise aself-discovery module, such as provided through the server 153, builtinto the software. As well, the system 40 can be expanded to includeutility monitoring and other applications.

In a conventional solar panel system, solar cells 12 are typicallymatched to make efficient solar panels, and solar panels are typicallymatched to make efficient solar arrays. In a conventional solar system,the output of a solar array having a plurality of conventional solarpanels, i.e. without DMPPT modules 18, can never match the sum of themaximum power of the conventional solar panels, and the conventionalpanels can never match the sum of the maximum power of the solar cells12. In additional to such inherit losses of power, environmentalconditions, e.g. such as but not limited to the time of day, season,weather, location, panel positioning, panel age, and/or panel condition,further degrade the short-term and/or long term efficiency of suchsystems.

FIG. 5 is a schematic block diagram of an exemplary solar panel system40, e.g. 40 a, having a plurality of strings 36, e.g. 36 a-36 n, ofenhanced solar panels 10, e.g. 10 a-10 k, routed through a combiner box48 and controlled through a modular power module housing 50 having oneor more enhanced inverter power modules 54, e.g. 54 a-54 j. FIG. 6 is aschematic block diagram 60 of an alternate exemplary solar panel system40 b having a plurality of strings 36, e.g. 36 a-36 n of enhanced solarpanels 10 having string-level combiner modules 62, routed through acombiner box 48, and controlled through a modular power module housing50 having one or more enhanced inverter power modules 54, e.g. 54 a-54j.

FIG. 7 is a block diagram of an exemplary distributed MPPT circuit 70for a distributed maximum power point tracker (DMPPT) module 18, whichtypically comprises an integrated or retrofitted module 18 for eachenhanced solar panel 18. DMPPT modules 18 associated with the enhancedsolar panels 10 overcome several problems inherent with conventionalsolar panels and the harvesting of power.

An input filter 74 is preferably attached to the input 72 of the DMPPTmodule 18, to help reduce EMI/RFI, as well as to supply protection fromsurges, etc. on the input side. This also helps in impedance matchingbetween the solar panel 10 and the DMPPT module 18, such as to improveMPPT tracking.

The exemplary DMPPT module 18 shown in FIG. 7 preferably comprises oneor more boost inductors 76, such as a dual inductively-coupled linkinductor 76 to boost the efficiency of the DC-DC conversion stage. Thishas the added benefit of splitting the power path, which provides anincrease in efficiency. At the present time, small inductor units 76cost less and weigh less than a single inductor design, and there isless chance for core saturation. Another benefit of this design is theincreased compensation factor. This allows a more stable distributed DCBus 42,52 to be produced, with less requirements for DC-ripple andoutput filtering 86.

Some DMPPT embodiments 18 use a multi-phase approach, wherein thecontroller 80 can reduce the current flow through the power switch 78,thus increasing efficiency and reducing the heat dissipation load. Thisalso allows the DMPPT 18 to improve power harvesting of the solar panels10. The controller 80 controls the switching of these power devices 78in a modified spread-spectrum switching scheme, to minimize EMI/RFIradiation of the modules 18. Low loss switching devices 78 are used toimprove overall efficiency. In some embodiments 18, these switchingdevices 78 comprise transistors, FETs, MOSFETs, IGBTs, or any otherpower-switching device 78 that meets the design criteria.

Two diodes typically provide rectification 84 for the DMPPT modules 18,thus reducing the power dissipation and providing a plurality of pathsfor the power flow. The rectification diodes 84 also effectively isolateeach DMPPT module 18 and associated solar panel 18 from the system array30, in case of total panel failure. Even if a DMPPT module 18 fails,this isolation still exists, if it was not the diodes 84 or the outputfilter 86 that failed. This increases the reliability of the system 40as a whole.

As seen in FIG. 7, a filter 86 is preferably attached to the output ofthe DMPPT modules 18, to help reduce EMI/RFI, and to provide protection,e.g. from surges, on the output side 90. The output filter 86 also helpsto stabilize the distributed DC bus 42,52 that feeds the solarinverter(s) 54.

The controlled production of DC output voltage at the DMPPT modules 18,having a higher voltage than the incoming voltage from the panels 10,reduces power transmission losses from the array 36 to the inverter(s)54. For example, for a higher voltage DC output that is also stabilized,to get the same amount of power from the array 36 to an inverter 54requires less current, since the power loss in the conductors is givenas I²R, where I is the current over the conductors, and R is theresistance. Therefore, the lower current due to the higher voltageresults in less line drop losses, and more power to the inverter(s) 54.

In addition, the inverters 54 run at better efficiency with a stable DCDistributed Bus 42,52. While other conventional inverters experiencebetter efficiency with a higher DC Bus input, as long as it is withinthe design specifications, the DMPPT module 18 may preferably boost thedistributed DC voltage from the array 36, to maximize this benefit.

FIG. 8 and FIG. 9 show typical Current-Voltage (IV) curves ofphotovoltaic solar panels. These demonstrate how the voltage moves overa wider range than the current with temperature and solar radiation. Themaximum power point for one or more panels moves during the day, andeach panel experiences different environmental conditions, even withinthe same system. The distributed maximum power point tracking modules 18and associated inverter system 40 provide several means to maximize thepower output over a wide range of such conditions.

The panel temperature 23 (FIG. 1) is monitored and reported back to aserver, such as an embedded server 153 associated with the inverterhousing 50, or to a server 55 associated with a particular inverter 54.This temperature value is also used as an input to the multi-level MPPTcontroller 80 (FIG. 7). An op-amp may preferably be used to scale thisvalue to be read by the controller 80, and is used as another controlinput to the controller 80 of the DMPPT module 18. In some embodimentsof the DMPPT modules 18, a lead wire and temperature sensor 24 exit fromthe DMPPT Module 18 and attach to the panel 18. In alternateembodiments, a temperature sensor 124 is collocated with the DMPPTmodule 18, such as inside a panel junction box.

The embedded server 153 may preferably supply an ambient temperature,such as taken outside of the inverter cabinet 54, or outside a webserver box, such as if another inverter is used at the site.

Operation of Distributed Maximum Power Point Tracking Modules.

FIG. 10 is time chart 112 showing operation states of the DMPPT 18,indicating DMPPT input voltage 102 i, and output voltage 102 o for anenhanced power module 10 having a DMPPT module 18. FIG. 11 is aflowchart of an exemplary process 122 for operation of an enhanced powermodule having a DMPPT module 18.

As a solar panel 10 starts producing a voltage 102 and current 104 whenlight is shining on it, this power is transferred to the distributed bus42 (FIG. 5) when it exceeds the voltage 102 to overcome the componentdrops and the forward voltage drop of the diode(s), such as shown in thediode circuits D2 and D3 seen in FIG. 21. In this regard, the systembehaves like a conventional solar panel array structure. In someembodiments of solar panels 10 having DMPPTs 18, once the voltage on thesolar panel 18 reaches a threshold voltage 116 (FIG. 10), e.g.approximately 4.5 to 6.5 Volts DC, the DMPPT Module 18 automaticallywakes up 126 (FIG. 11), and starts performing the necessary checks128,130, before switching over to RUN Mode 132.

As the voltage 102 of the solar panel 18 increases, the DMPPT 18 startsboosting the voltage 102 from the panel 18 to the common distributionbus 52 feeding the solar inverters 54. This wait is necessary to preventthe loss of control power from the controller circuit 70 (FIG. 7) whenswitching begins. By using control inputs, the system tracks the maximumpower point of the solar panel 18, and boosts the voltage out to thedistributed DC Bus 52 feeding the solar inverter(s) 54.

Since the voltage 102 i is boosted 102 o, the system as a whole reachesstriking voltage for the solar Inverter 54 in a shorter period than aconventional array of panels 10 would without DMPPT Modules 18.

Furthermore, the system 40 as a whole operates longer before shuttingdown at the end of a power generation period 118, e.g. such as atsunset, dusk or evening 119 for externally mounted solar panels 18.Since the function of maximum power point tracking (MPPT) is performedat the panel level, several other issues associated with solar panels 10are addressed as well.

For example, problems with mismatched or different manufacturers can beeliminated with the DMPPT units 18. As seen in FIG. 29, solar panels 10on different planes and orientations can be combined into the samesystem, without any de-rating or loss of harvest from the array 34. Theoverall efficiency of the array is increased, because the MPPT is doneon a per panel basis, and not on the average of the entire system. Incontrast to conventional solar systems, string mismatches are not anissue, due to the active nature of the DMPPT Modules 18. Conductionlosses are reduced, thus allowing more energy to be harvested andtransmitted to the inverter 54 for grid conversion. The overallefficiency of the array 34 is increased, because the panel output isprocessed, monitored, and controlled on a per panel basis, and not basedupon the average of the entire string 36 or array 34. Safety featuresare built into the design for fire safety, monitoring, and several otherfuture applications.

Overall, the DMPPT Module 18 addresses many of the current limitationsof solar power, such as by providing longer harvest times withpanel-level DMPPT modules 18, by providing “Early-On” and “Late-Off” forextended harvest times. Since the output from the solar panels 10 isboosted, the usable power is converted by the inverter 54, because thestriking voltage is reached sooner and can be held longer, therebyresulting in an increase in harvestable power from each of the solarpanels 10.

As well, some embodiments of the DMPPT modules 18 may preferably bereprogrammable or updatable, such as over the communications link 22,wherein different algorithms may be sent and stored within the DMPPTcontrollers 80, such as for modifying start up, operation, safety andshutdown operations.

DMPPT modules 18 also help to reduce the effects of partial shading onsolar arrays 34. In conventional solar panels, partial shading of asingle cell 12 causes the entire panel and string in which it isconnected to reduce power output, and also increases loses due to stringmismatch, by lowering the MPPT point for an entire solar array. Incontrast to conventional panels, the DMPPT modules 18 can controllablycompensate for partial shading at the panel level, to boost the DCoutput signal 102 o.

Test Platform.

A test platform was installed to test the benefits and operation of theDMPPT modules 18. The test bed utilized forty-eight solar panels 10,rated at 170 watts, connected in six strings of eight 170-watt panelseach. FIG. 12 is a schematic layout view 140 of the exemplary test bedsolar array 34 comprising a plurality of solar panels 10, wherein aportion of the panels in one or more strings further comprise DMPPTmodules 18. A first group 142 a comprising three strings 36 a,36 b and36 c having different sample orientations across the array 34 includedDMPPT modules 18, while a second group 142 b comprising three strings 36d,36 e and 36 f having different sample orientations across the array34, did not include DMPPT modules 18.

The system was connected to two identical conventional solar inverters144, e.g. 144 a,144 b for connection to a public AC grid, wherein thefirst string group 142 b was fed into the first conventional inverter144 a, and the second string group 142 b was fed into the secondconventional inverter 144 b. In the test platform 140, each of theconventional solar inverters 144 a,144 b was rated at 4,080 Watts PeakDC.

FIG. 13 shows the relative proportion and size of an exemplary solararray having a capacity of approximately 170 W, comprising a pluralityof enhanced solar panels, wherein a portion of the panels in one or morestrings further comprise DMPPT modules 18.

The panels on the test bed are laid out to give a fair representation ofsolar illumination. One half of the panels are modified with the DMPPTmodules 18, while the other half of the panels are left unmodified, i.e.standard solar panels. Each set feeds into a similar sized solarinverter from the same manufacturer. Data is to be gathered over aperiod of time to evaluate specific design parameters for the DMPPTmodules 18. Since the strings 36 are set adjacent to each other, shadingcan be introduced upon the system, such as by using cardboard cutoutsand sliding them over the top the solar panels 10.

Enhanced Inverter System Operation and Monitoring.

FIG. 14 is a block diagram of an exemplary system 40 comprising amodular power inverter housing 50 housing having one or more enhancedinverter modules 54, e.g. 54 a-54 j, a central interface 152, a database154, and connectable 155 to one or more local or remote monitoring orcontrol devices 156,160, such as for interaction with a user USR.

In some system embodiments, the modular power inverter housing 50 ispowered by the AC bus 56, e.g. such as by the AC grid 58, wherein thehousing 50 may be powered by a public AC grid 58 even when the powerarray(s) 34 are down. In other system embodiments 40, the modular powerinverter housing 50 is powered by the DC bus 42, 52 e.g. such as by thesolar arrays(s) 34, wherein the housing 50 may be powered off-grid, evenwhen the AC grid 58 is down. In some alternate system embodiments, themodular power inverter housing 50 is powered either off-grid 42,52 oron-grid 58, such as depending on available power.

As seen in FIG. 14, a central monitoring and control interface 152interacts with each of the inverters 154, e.g. the enhanced inverters 54a-54 j. Each of the enhanced inverters 54 preferably comprise adedicated server 55 (FIG. 5, FIG. 6), e.g. an embedded web server 55, ormay communicate with a system server 153, e.g. an embedded system server153, associated with the inverter housing 50.

The data collected from the power panels 10, e.g. the solar panels 10,the enhanced inverters 54, e.g. solar inverters 54, and other equipmentwith the system 40, can be displayed in near real-time, such as througha local device 156 or remote device 160, e.g. over a network 158, suchas but not limited to a local area network (LAN) a wide area network(WAN), or the Internet. This collected data can also be sent, such asthrough a server 153, and logged into a database 154. The exemplarysystem 40 seen in FIG. 14 may therefore preferably provide detailedtrending analysis and/or performance tracking over the lifetime of thesystem. The system server 153, e.g. an embedded web server 153,typically gathers information and provides presetting of controls forthe entire system 40, right down to the individual panels 10, throughcommunication links 22 to panel DMPPT modules 18.

The DMPPT module controller 80 (FIG. 7), e.g. such as comprising adigital signal processor 80, typically outputs data in a slave mode,such as by reporting data back to an associated embedded server 54 whenrequested, through one of several means, e.g. such as but not limited towired or wireless transmission 22. The controller 80 also typicallyaccepts measured parameters from the embedded controller 54 pertainingto the local ambient temperature 25 (FIG. 1) and the solar insolation,i.e. the intensity of incident solar radiation These parameters, alongwith the data collected at the panel 10, provide control inputs to theprogram performing the MPPT function on a distributed, i.e. local panel,level.

In some system embodiments 40, the communication links 22 between theDMPPTs 18 and the embedded server(s) 153,55 comprise either a multi-dropsingle twisted pair RS-485 communications line 22, or a wireless radiolink 22. In some system embodiments, the use of wireless communicationlinks 22 may be preferred, such as to reduce the wiring cost, therebyreducing the overall cost of the system 40.

In some embodiments, the protocol used for the communication links isModBus, such as RTU RS485 for the wired system, or a wireless tree meshsystem with self-healing/discovery capabilities for wirelesscommunication links 22. Such ModBus protocols are preferably designedfor harsh environments, minimizing or eliminating lost packets of data.

All distributed data is gathered and passed 22, e.g. via the RS-485ModBus links 22, and then the embedded server 54 at the inverter cabinet50 formats this into a viewable web page 157 (FIG. 14) for the user USR.This collected data can also be streamed out to another server, e.g.156,160 for data logging and trending applications.

The heartbeat signal rides on the universal broadcast address, and thissynchronizes all of the panels 10 within a few microseconds of eachother for their operation. Another defined address broadcasts theambient temperature and solar insolation from the server 153 to each ofthe DMPPT Modules 18. If communications are lost, or if a “Fire” signalis broadcasted, then the DMPPT Modules 18 automatically shut down, toremove high voltage from their input 72 and output 90.

Modular Design of Solar Inverter Units.

FIG. 15 is a block diagram of a modular inverter housing 50, such as aModel No. ASPM-2-70 KW, available through Accurate Solar Systems, Inc.of Menlo Park Calif., having two 35 KW enhanced inverters 54 installed,such as a Model No. ASPM-1-35 KW, available through Accurate SolarSystems, Inc. of Menlo Park Calif., having a total rating of 70 KW. FIG.16 is a block diagram of a modular inverter housing 50 having three 35KW enhanced inverters 54 installed, e.g. Model No. ASPM-1-35 KW, ratedfor 105 KW. FIG. 17 is a block diagram of a modular inverter housing 50housing having four 35 KW enhanced inverters 54 installed, e.g. ModelNo. ASPM-1-35 KW, rated for 140 KW. While the exemplary enhancedinverters 54 described above are rated at 35 KW each, some alternateembodiments of the enhanced inverters are rated 4 kilowatts each,wherein the system 40 can operate even closer throughout the day.

The modular inverter housing 50 may preferably house a plurality ofinverters 54, to reduce cost, increase efficiency, and improveperformance of the system 40. As well, the use of a modular enhancedinverter 54, such as but not limited to a 35 kW inverter 54, is readilycombined or stacked to provide a wide variety of capacities for a system40, such as for a 35 kW system, a 70 kW system 40, a 105 kW system 40,or a 140 kW system 40, which may be housed in one or more types ofmodular inverter housings 50.

Each cabinet 50 typically comprises associated transformers, outputcircuitry, input circuitry, and communications 151 with the embedded webserver 153. The smallest current cabinet 50 houses a single 35 kW module54. The next step is a larger cabinet 50 that houses between two andfour of 35 kW enhanced inverter modules, depending on the powerrequired.

In the modular inverter housing systems 50, such as seen in FIG. 15,FIG. 16 and FIG. 17, if an enhanced inverter 54 goes down, the otherscontinue to deliver power to the AC bus 58. Therefore, a single faultwill not bring the entire system 40 down. The enhanced inverter units 54communicate with each other, such as through the embedded web server153.

In some system embodiments 40, one of the enhanced inverters 54initially comes on as the system 40 starts up, such as to increaseefficiency. As the available power increases, the next enhanced inverterunit 54 is signaled to come online, and so on, such that the system 40operates at near peak efficiency for as much time as possible, therebyproviding more system up time in larger systems. Therefore, in somesystem embodiments 40, the use of multiple enhanced modules 54 wastesless energy, as the system 40 only turns on inverters 54 that can besupported by the array 34.

In the modular inverter housing systems 50, such as seen in FIG. 15,FIG. 16 and FIG. 17, each of the enhanced inverter modules 54, e.g. suchas but not limited to being rated at 4 kW or 35 kW apiece, maypreferably be hot swappable.

Advanced Diagnostics and Monitoring of Enhanced Power Systems.

Since embedded web servers 153,55 communicate with the solar inverters54, the solar panels 10, and any other associated equipment, the system40 may preferably provide a near real-time view of the current status ofthe system 40 as a whole. If a problem occurs, then the operator USR isnotified by various means, e.g. such as through the user interface 157.

Most conventional solar power inverter systems typically provide asingle DC input voltage and a single current measurement at the inverterlevel, which is based upon the sum of an entire array. In contrast,while the enhanced power inverter system 40 provides the current,voltage, and power of each of the arrays 34, the enhanced power invertersystem 40 may preferably provide the status and performance for eachindividual panel 10 and string 36, such that troubleshooting andmaintenance is readily performed.

Smart Switching Technology.

FIG. 18 is a simplified schematic circuit diagram of an exemplary powersection 180 for an enhanced inverter module 54, wherein the enhancedinverter 54 uses a three-phase half bridge IGBT driven power stage, suchas provided with IGBTs 192, driver cards 188, and fiber optic links 190.

Most conventional inverter systems use a standard high frequency pulsewidth modulation (PWM) method that, while it performs basic signalinversion, has many inherent disadvantages.

FIG. 19 shows a resultant output power signal pulse train 200, basedupon active elimination of harmonics by an enhanced inverter module 54,wherein the power signal is processed using sine weighted pulses. In theenhanced pulse width modulation (PWM) provided by the enhanced invertersystem 54, some of the edges, e.g. 204,206, are dynamically linked toother edges in the firing sequence. This has the benefit of simplifyingthe overall inverter 54, as well as actively eliminating all thirdharmonics. The enhanced inverter system 54 reduces or eliminatesharmonics, by controlling where the rising edges 204 and falling edges206 of the pulse train 200 occur.

Combining these two features, it is possible to generate a modifiedsmart switching PWM signal 200 that has very low harmonic content, alower carrier switching speed, and improved efficiency. This switchingscheme 200 allows a relatively simple filter 356 (FIG. 26) to be used,which reduces weight and cost, and improves efficiency. The cutoff pointfor the filter 356 is preferably designed for the nineteenth harmonic,thus improving vastly over conventional pulse width modulation methods.For example, for an enhanced 35 kW inverter design, the power savingsfrom switching alone ranges from about 650 Watts to 1 kW of power.

For example, the following equation provides the third harmonics of aseven pulse modified PWM waveform, as shown:

H03=(cos(p1s*3*pi/180)−cos(p1e*3*pi/180)+cos(p2s*3*pi/180)−cos(p2e*3*pi/180)+cos(p3s*3*pi/180)−cos(p3e*3*pi/180)+cos(p4s*3*pi/180)−cos(p4e*3*pi/180)+cos(p5s*3*pi/180)−cos(p5e*3*pi/180)+cos(p6s*3*pi/180)−cos(p6e*3*pi/180)+cos(p7s*3*pi/180)−cos(p7e*3*pi/180)+0)/(a01*3)

where “a01” is the power of the fundamental waveform, p stands forpulse, the number next to p indicates the number of the pulse, s standsfor the start of the pulse, and e stands for the end of the pulse, e.g.p1 s indicates the start of the first pulse, and p1 e indicates the endof the first pulse. Also, the first three pulses and the ending fifthpulse are linked to the others, to eliminate the third harmonics.

A microprocessor 352 (FIG. 26), such as located at a server 153 embeddedwithin the inverter housing 50, generates a calculated smart switchingpulse train signal 200, such as shown above. The calculated smartswitching pulse train signal 200 is then passed 366 (FIG. 27) to thedriver cards or boards 188, such as through fiber optic links 190 or viacopper wire 190. The driver boards 188 then convert these digital pulses202 (FIG. 19), e.g. 202 a-202 g, into power driving signals for theIGBTs 192. The IGBTs 192 controllably follow the turn-on pulses 204 andturn-off pulses 206 of the original smart switching pulse train signal200, thus switching the high DC Bus voltage. This switching power isthen transformed to the AC grid voltage 58 by a transformer 355 (FIG.26) and a relatively small filter 356 (FIG. 26). The resultant outputsine wave is very low in distortion. The use of smart switching 200inputs to the enhanced inverters 54 therefore reduces power loss,reduces harmonics, reduces filter requirements, and reduces cost.

Controller and Power Supply.

As described above, each of the DMPPT modules 18 are typically poweredfrom their respective solar panels 10, such as to reduce the wiringrequirements and improve the overall efficiency of the system 40. FIG.20 is a schematic circuit diagram of an exemplary self-power section 220of a DMPPT module 18, which generates local control voltage for theDMPPT module 18 from the solar panel 10.

In some embodiments, when the solar panel 10 begins generating about 4.5to 6.5 volts DC, there is enough power to start the DMPPT module 18. Oneof the benefits realized by this configuration is that the system 40 asa whole can wake up automatically, off the external AC grid 58. For asystem 40 configured with externally mounted solar panels 10 that areexternally mounted on the surface of the Earth E, e.g. such as but notlimited to stand-alone panels 10 or building-mounted panels 10, the userUSR is able to observe this wake up phenomena as the sun S rises in themorning, and as it sets in the evening, when the DMPPT modules 18 shutdown for the night.

Boost Circuits for DMPPT Modules.

FIG. 21 is a schematic circuit diagram of an exemplary boost circuit 250for a DMPPT module 10.

Voltage and Current Monitoring for Distributed Multi-Point Power PointTracking Modules.

FIG. 22 is a schematic circuit diagram of an exemplary current sensor270 for a DMPPT module 18, such as implemented by a V/I monitor 82 (FIG.7) and associated hardware, e.g. a current loop 83 (FIG. 7). FIG. 23 isa schematic circuit diagram of an exemplary voltage sensor 290 for aDMPPT module 18. The output voltage and current are reported back to theembedded server 153 at the inverter cabinet 50, while used locally bythe DMPPT controller 80 (FIG. 7) to provide stable regulated output 90for the DC distribution bus 42,52 (FIG. 5, FIG. 6). The input voltageand current are used by the on-board controller 80, e.g. DSP, as part ofthe multi-level MPPT program.

The output voltage also plays into this control loop. A Hall-effectDC/AC current module and a 10 M ohm voltage dividing resistor networktransforms these signals to an op-amp for scaling, and are thenprocessed by the controller 80, e.g. DSP 80. This forms the basis of aper panel monitoring system.

System Safety and Use of Crowbar Circuits.

FIG. 24 is a schematic circuit diagram of an exemplary output safetyswitch 310 for a DMPPT module 18. FIG. 25 is a schematic circuit diagramof an exemplary crowbar circuit 330 for a DMPPT module 18. The enhancedsolar panel 10, such as seen in FIG. 1, preferably providessurvivability from an output short circuit. As seen in FIG. 7, an inputcrowbar circuit 96, triggered by the microprocessor 80, is placed acrossthe incoming power leads from the panel 10. In case of a fire, or anyother maintenance procedure that requires the system to be de-energized,the input crowbar circuit 96 is triggered, thereby shorting out thesolar panel 18. An output crowbar circuit 98 may also preferably beprovided, such as to charge down capacitors when the unit is shut down.

The crowbar circuits 96,98 may be activated for a wide variety ofreasons, such as for emergencies, installation, or maintenance. Forexample, during installation of the enhanced panels 10, the associatedDMMPT modules 18 prevent high voltage from being transmitted to theoutput terminals 19 a,19 b (FIG. 1), until the panel is fully installedinto the system 40. As well, if maintenance functions need to beperformed near or on one or more panels 10, one or more of the solarpanels 10 can be turned off, such as by triggering the crowbar circuits96,98 through the DMPPT controllers 80.

The crowbar circuits 96,98 conduct and hold the solar panel 18 in ashort-circuit condition until the voltage or current falls below thedevice's threshold level. To re-activate the solar panel 10, the currentis typically required to be interrupted. This can typically be doneeither by manually breaking the circuit, or by waiting until thesunlight fades in late evening. This means that the system automaticallyresets its DMPPTs 18 during a period of darkness, e.g. the night.

Currently, one of the most cost effective crowbar circuits comprises asilicon controlled rectifier (SCR) 330. This allows the crowbars 96,98to continue to function, even though the main circuits control power hasbeen shorted. This removes the danger of high voltage DC power from thepersonnel, e.g. on a roof of a building where solar panels 10 areinstalled. The DMPPT system 18 automatically resets itself during thenight, thus allowing for the completion of the work. If it is necessaryfor another day, the system 40 can operate in one of two modes. In afirst mode, such as when communications 22 are present with the host 50,the host 50 can instruct the DMPPT devices 18 to shut down, thusallowing another period of safe work, e.g. on the roof. In a secondmode, such as when there are no communications 22 with the host 50, theDMPPT module 18 may preferably fire, i.e. activate, the crowbardevice(s) 96,98. To prevent unnecessary shutdowns, thisnon-communication method may preferably only occur if a status bit hasbeen saved, e.g. in EEPROM memory at the module 18, indicating a fire ormaintenance shutdown.

The current crowbar circuit 330 implemented for the DMPPT Module 18 isan SCR with its associated firing circuitry. The main control software,e.g. within the system server 153, preferably allows for a maintenanceor fire shut down of the solar array system. This operates on a panelper panel basis, thus providing a safe solar array shutdown. The hostsystem housing 50 can display the current array DC voltage, to indicatewhen it is safe to enter the roof area. The host system housing 50 maypreferably be tied into the fire alarm system of the building, or may becontrolled by a manual safety switch located by the host system itself.This addition to the DMPPT Modules 18 therefore enhances overall systemperformance, and improves safety for personnel.

Enhanced Inverter Power Circuit Operation.

FIG. 26 is a schematic block diagram 350 showing microprocessor-basedpulse width modulation 354 of an enhanced inverter 54, such as toeliminate one or more levels of harmonics. FIG. 27 is flowchart of anexemplary PWM harmonic reduction process 360 for an enhanced inverter54. As seen in FIG. 26, a microprocessor 352 may preferably be used toprovide a driving signal 354 to each of the enhanced inverters 54. Forexample, as seen in FIG. 27, for a DC signal received 362 at theenhanced inverter 54, either the DC power 42,52 from the panels 10, orthe AC bus power 58, may be used to turn on 364 the power to theinverter transistors 192 (FIG. 18), which may preferably compriseinsulated gate bipolar transistors (IGBTs) 192. A special signal 354(FIG. 26), which may preferably comprise a smart switching pulse train200 (FIG. 19), e.g. such as but not limited to switching at 1.68 KHz, issent from the microprocessor 352 at the embedded server 153 (FIG. 14),to switch the DC bus through the driver cards 188 (FIG. 18) and provideactive elimination of one or more harmonics, such as to controllablyreduce or eliminate the harmonics from the DC signal, e.g. thirdharmonics 3, 9, 15, etc. The AC signal output 368 from the enhancedinverter 54 provides increased power over conventional inverter systems.

Since the inverter 50 is built in module blocks 54, for a larger system40 each inverter block 54 may preferably turn on when needed to increasesystem efficiency. Solid-state inverters 54 presently run better oncethey have more than about 45 percent load. Therefore, for a 140 kWsystem 40, as power increases through the day, a first module 54 willturn on to provide power until there is enough power for the secondmodule 54. The second module 54 will come on and the two modules 54,e.g. 54 a and 54 b will share the load (and still above the 45% point)until a third module 54 is needed. The same is true until all fourmodular inverters 54 are on. Later in the day, when power from the solararray 34 begins dropping off, each modular inverter 54 will drop off asnecessary, until the system 40 shuts down for the night. This keeps thesystem 40 running at peak efficiency longer than a single largeinverter, thus generating more power for the AC grid 58.

The use of smart switching of the inverters 54, as described above,delivers more power to the grid, since less solar power is convertedinto heat from the switching of the transistors. Furthermore, since asmaller filter is required (due to harmonic cancellation), there is morepower available for pumping to the grid.

Another benefit of the modular system 40 is redundancy. For example, ina system having more than one enhanced inverter 54, if one enhancedinverter 54 fails for some reason, the entire system 40 does not comedown. The system can continue to pump power out to the AC grid 58 withwhat capacity is left in the system 40.

FIG. 28 is an exemplary user interface 400, such as comprising a webpage 157 (FIG. 14), for monitoring and/or control of an enhanced powerharvesting system 40 comprising enhanced inverters 54, and power modules10 having DMPPT modules 18. The exemplary user interface 400 seen inFIG. 28 may typically comprise any of system, array and/or componentlevel status 402, control 404, logs 406 for one or more panels 10,system reports 408, and revenue tracking 410. For example, an exemplarysystem status screen 412 is seen in FIG. 28, such as to indicate currentoperating status of different strings 36 of solar panels 10.

As seen in FIG. 28, a first string 36 of panels comprises six panels 10,wherein panels 1-4 and 6 in the string are indicated 414 a as beingonline and OK, while the fifth panel 10 in the first string is indicated414 a as being a problem and is currently taken offline. As also seen inFIG. 28, a second string 36 of panels comprises six panels 10, whereinpanels 1-6 in the second string are indicated 414 b as being shutdownfor service, such as controlled 416 through the user interface 400.

The user interface 400 may typically be accessed through a wide varietyof terminals, such as directly through an embedded server 153, locallythrough a connected terminal 156, or at another terminal 160, such asaccessible through a network 158. In some embodiments, the system 40 mayprovide other means for alerts, status, and/or control, such as but notlimited to network communication 155 to a wireless device 160, e.g. suchas but not limited to a laptop computer, a cell phone, a pager, and/or anetwork enabled cellular phone or PDA.

As each of the panels 10 preferably comprises DMPPT functionality 18,wherein the DMPPTs provide monitoring at the panel level, the system 40is readily informed, such as over the communication links 22 between theDMPPTs 18 and the invertors 54 or housing 50, of the operating status ofeach panel 10 in any size of array 34.

Furthermore, the DMPPTs 18 similarly provide troubleshooting anddiagnostics at the panel level. For example, if there is a problem withone or more panels 10, such as not working, shut down locally by acontroller 80, dirty, or shaded, the system 40 will be informed over thecommunication links 22 of any and all panel-level information, and canalert the user USR. All information from the panels 10 is typicallylogged into a database 154, where performance, history trends, andpredications of future performance can be calculated. The database 154may preferably be connectable through a network 158, such as theInternet, i.e. the World Wide Web, wherein viewing, and even controland/or maintenance, may be done through a web browser at a remoteterminal 160.

As each enhanced panel 10 is connected to an associated DMPPT module 18,problems can be identified and pinpointed for both broken andsub-performing panels 10, wherein such panels 10 may readily be foundand replaced, i.e. the system 40 identifies the exact panel(s) with aproblem, thus significantly reducing the time required for repairs.

FIG. 29 shows an enhanced power harvesting system 40 located on theEarth E, wherein one or more panels 10 within a string 36 have differentangles (0, 45, 90) or orientations (E, W, N, S). Conventional solarpanels systems require solar panels having different angles of tilt tobe serviced by different inverters. However, since the output of theDMPPT modules 18 at the panel level can be regulated, enhanced panels 10having different tilt angles 422 can be fed into the same inverter, e.g.an enhanced inverter 54. The enhanced system 40 therefore allows panelsto be mixed, such by varying tilt 422, from flat (0 degrees) through 90degrees, and/or by varying directional orientation 424, by mixing East,West, South and/or North facing panels 10.

As well, since the output of the DMPPT modules 18 at the panel level canbe regulated, strings 36 having different lengths of enhanced panels 10may be fed into the same inverter, e.g. an enhanced inverter 54 or evena conventional inverter. For example, if one string 36 has an extrapanel 10, or shorts a panel 10, the DMPPT modules can adjust the outputof the remaining panels 10 in a string 36 to allow this “incorrect”string size to function in the system 40, without adverse affects.

Similarly, the use of DMPPT modules 40 allows different size panels ordifferent manufacturers to co-exist in the same array 34. Therefore,instead of having to buy all of the panels from a single manufacturer toreduce mismatch problems, the DMPPT allows the use of various panels andeven different wattages within the same system 40. Such versatilityprovides significant architectural freedom in panel placement anddesign, wherein solar panels equipped with an associated DMPPT module 10allow unique layouts to accommodate different architectural features onany building or facility.

Furthermore, the use of DMPPT modules 40 addresses panel and stringmismatch losses. At the present time, no two panels 10 are alike, andoften are specified with a plus or minus 5 percent rating. Whileconventional solar panel strings 36 operate only as well as the weakestpanel 10 in the string, the DMPPT modules 18 can adjust the output ofthe panels 10 to boost their output. Similarly, the DMPPT modules 18 fora string 34, such as controlled by the server over the communicationslinks 22, can boost the power as needed to reduce or even eliminatestring mismatch losses.

Block Diagram of Operation Software.

The software for the DMPPT modules 18 can be broken down into varioussections as most are interrupt driven. When the modules 18 wake up inthe morning, they each perform a routine check to ensure that everythingis functioning properly. The modules 18 preferably check the status of afire alarm flag, which is stored in EEPROM inside themicroprocessor/controller 80 of the DMPPT Module. The microprocessorcurrently implemented for the controller 80 includes FLASH, EEPROM, andSRAM memories on the chip.

While the modules 18 watch the communications line 22 for activity, suchas to see if the panel 18 needs to shutdown before power levels rise toa dangerous level. If necessary, the DMPPT Module 18 fires the crowbarcircuit 96,98 to remain off line. Otherwise, it will proceed to the waitstage, until enough power is available for it to perform its functions.

Multiple Power Inputs for the Enhanced Inverter Units.

Since the inverter design has been modified so that the MPPT has beenshifted to maximize harvest, the enhanced inverters, as well as theDMPPT modules may readily be adapted for different means of powergeneration, such as but not limited to fuel cells, wind power, Hydro,Batteries, Biomass, and Solar power. The inverters can operate at 50 Hz,60 Hz, or 400 Hz to cover a vast range of applications. The system canalso be designed for on-grid or off-grid applications.

While some embodiments of the structures and methods disclosed hereinare implemented for the fabrication of solar panel system, thestructures and methods may alternately be used for a wide variety ofpower generation and harvesting embodiments, such as for fuel cells orbatteries, over a wide variety of processing and operating conditions.

As well, while some embodiments of the structures and methods disclosedherein are implemented with a server 153 within the modular inverterhousing 50, other embodiments may comprise dedicated servers 55 withineach of the enhanced inverters 54, which may also be in combination witha housing server 153.

Furthermore, while the exemplary DMPPT modules 18 disclosed herein arelocated at each of the panels, dedicated DMPPT modules can alternatelybe located at different points, such as ganged together locally near thepanel strings 36. In present embodiments, however, the DMPPT modules 18disclosed herein are located at each of the panels 10, such as toprovide increased safety, since the crowbar circuitry 96,98 is locatedat the panel, and upon activation, no high voltage extends from thepanels on the output connections 21.

Accordingly, although the invention has been described in detail withreference to a particular preferred embodiment, persons possessingordinary skill in the art to which this invention pertains willappreciate that various modifications and enhancements may be madewithout departing from the spirit and scope of the claims that follow.

1. A control module for a power panel, comprising: input connectionsthat are connectable to one or more DC power cells; output connectionsthat are connectable to an inverter; a signal processing circuitconnected to the input connections and to the output connections; acrowbar circuit that is located across the input connections; and acontroller that is connected to the signal processing circuit, whereinthe controller comprises a communications link that is connectable to aserver; wherein the controller is configured to drive the crowbarcircuit to short across the input connections to shut down the DC outputof the power panel in response to an input signal that is sent from theserver and received at the controller over the communications link. 2.The control module of claim 1, wherein the input signal to shut down theDC output of the power panel corresponds with any of service, safety, orfire.
 3. The control module of claim 1, wherein the control modulefurther comprises a mechanism for sending a data signal to the serverover the communications link.
 4. The control module of claim 3, whereinthe input signal sent from the server and received at the controller isat least partially responsive to the data signal.
 5. The control moduleof claim 3, wherein the data signal comprises any of input voltage data,input current data, output voltage data, output current data,temperature data, or insolation data.
 6. The control module of claim 1,wherein the DC power cells comprise any of solar panels, fuel cells, orbatteries.
 7. The control module of claim 1, wherein the communicationslink comprises any of a wired communications link or a wirelesscommunications link.
 8. The control module of claim 1, wherein thecontrol module is any of reprogrammable or updatable in response toinstructions received over the communications link, to modify any ofoperation, safety and shutdown operations.
 9. The control module ofclaim 1, wherein the controller is configured to drive the crowbarcircuit to short across the input connections to shut down the DC outputof the power panel if communications are lost with the server over thecommunications link.
 10. A process, comprising the steps of: providing apower panel, comprising a control module comprising input connections,output connections that are connectable to an inverter, a signalprocessing circuit connected to the input connections and to the outputconnections, a crowbar circuit that is located across the inputconnections, and a controller connected to the signal processingcircuit, and a plurality of DC power cells connected to the inputconnections of the control module; providing a communications linkbetween the controller and a server; receiving an input signal at thecontrol module over the communications link, wherein the input signal istransmitted from a server; and driving the crowbar circuit to shortacross the input connections to shut down the DC output of the powerpanel in response to the received input signal.
 11. The process of claim10, wherein the step of driving the crowbar circuit to shut down the DCoutput of the power panel is performed for any of service, safety, orfire.
 12. The process of claim 10, further comprising the step of:sending a data signal to the server over the communications link. 13.The process of claim 12, wherein the input signal is at least partiallyresponsive to the data signal.
 14. The process of claim 12, wherein thesent data signal comprises any of input voltage data, input currentdata, output voltage data, output current data, temperature data, orinsolation data.
 15. The process of claim 10, wherein the DC power cellscomprise any of solar panels, fuel cells, or batteries.
 16. The processof claim 10, wherein the communications link comprises any of a wiredcommunications link or a wireless communications link.
 17. The processof claim 10, further comprising the step of: reprogramming or updatingthe control module in response to a instructions received over thecommunications link, to modify any of operation, safety and shutdownoperations.
 18. The process of claim 10, further comprising the step of:automatically driving the crowbar circuit to short across the inputconnections to shut down the DC output of the power panel ifcommunications are lost with the server over the communications link.19. A server, comprising: at least one processor; and a communicationslink for connection to a power panel, wherein the power panel comprisesa control module comprising input connections, output connections thatare connectable to an inverter, a signal processing circuit connected tothe input connections and to the output connections, a crowbar circuitthat is located across the input connections, and a controller connectedto the signal processing circuit, and a plurality of DC power cellsconnected to the input connections of the control module; wherein the atleast one processor is controllable to send an input signal to thecontrol module over the communications link to drive the correspondingcrowbar circuit to short across the input connections to shut down theDC output of the power panel.
 20. The server of claim 19, wherein theinput signal to shut down the DC output of the power panel correspondswith any of service, safety, or fire.
 21. The server of claim 19,wherein the server further comprises a mechanism for receiving a datasignal from the control module over the communications link.
 22. Theserver of claim 21, wherein the input signal sent from the server is atleast partially responsive to the data signal.
 23. The server of claim21, wherein the data signal comprises any of input voltage data, inputcurrent data, output voltage data, output current data, temperaturedata, or insolation data.
 24. The server of claim 19, wherein the DCpower cells comprise any of solar panels, fuel cells, or batteries. 25.The server of claim 19, wherein the communications link comprises any ofa wired communications link or a wireless communications link.
 26. Theserver of claim 19, wherein the at least one processor is controllableto send instructions to the control module over the communications link,to modify any of operation, safety and shutdown operations.
 27. Theserver of claim 19, further comprising: a user interface for any ofmonitoring or control of the power panel.